GSM phones require a small electronic chip, called a SIM card, to be inserted into a slot in the handset. This SIM card is the “heart” of your phone – it contains your mobile phone number, your phone book, and all of your registration information. The Mobal GSM SIM card provides you with access to over 320 GSM networks in over 160 countries

Well said. I should note that a SIM card will not store your pictures. So, when you change phones, like I did, you may lose all of that unless.......you download the P2K file on this site. I'm so glad I found this place.

its more of your line than anything, yeah it can store some names, but is very limited in every way (only stores a certain amount, i think the newest ones are about 200 havent checked, and they dont support more than one number for a contact, etc) i leave my phone book on my phone, but this kind of stuff is old news in the middle east and europe, i still don't undresstand why the states and canada are SOOOOOOOOOOOOOOOOOOOOO far behind when it comes to cell phone technology when they have lots of other good technologies?